This is an application to examine the effects and mechanisms of action of parental and grandparental drug use on child and adolescent development. We seek 5 years of support to collect and analyze data on the children of the members of the Seattle Social Development Project (SSDP) panel. SSDP (J. David Hawkins, PI) is a theory-driven study with a preventive intervention nested within its early years. The Intergenerational Project (TIP, Karl G. Hill, PI) has studied the firstborn children of SSDP members, the SSDP G2 parents themselves, and their partners. Earlier work focused on effects of parent drug use on children. We propose a follow-up study to extend data collection and analysis for an additional three waves as most G3 children transition into adolescence. This will provide adequate sample sizes for examination of 1) the impact of prior and current parental and grandparental drug use on development and drug use initiation, 2) mechanisms through which prior and current parental and grandparental drug use may affect child development and drug use initiation, and 3) the degree to which benefits from preventive intervention experienced by G2 when they were children affect G3's developmental environment, G2's parenting practices, and G3's developmental outcomes. The study builds on an existing 20-year longitudinal study, and will run parallel to its extension into the 30's, without scientific or budgetary overlap. The proposed study presents a unique opportunity to examine factors linking drug use across three generations and to analyze the effects of G2's drug use during adolescence and early adulthood on their parenting behaviors and on their children's outcomes. Study findings will advance understanding of the effects of parental and grandparental drug use during adolescence and early adulthood on children's development, behavior, and drug use initiation and will provide specific targets for the design of preventive interventions aimed at breaking cycles of intergenerational transmission of drug use. PUBLIC HEALTH RELEVANCE: The study will advance understanding of the effects of parental and grandparental drug use during adolescence and early adulthood on children's development, behavior, and drug use initiation and will provide specific targets for the design of preventive interventions aimed at breaking cycles of intergenerational transmission of drug use.